1. Field of the Invention
The present invention relates generally to a liquid crystal display (LCD) device and a method for manufacturing the same, and more particularly to an in-plane switching liquid crystal display (IPS-LCD) device and a method for manufacturing the same.
2. Prior Art
The invention of liquid crystal display (LCD) devices has revolutionized the way information is displayed. Its overwhelming application in almost all aspects of electronic products guaranteed its success in the market. However, for many years, LCD devices have suffered from its narrow viewing angles. This drawback is solved by many techniques. Among them, the most popular one is the so-called in-plane switching (IPS) technique, which is disclosed in U.S. Pat. No. 5,600,464, for example.
Referring to FIG. 3, a conventional IPS-LCD device 100 is illustrated. The IPS-LCD device 100 comprises a source line 102, a gate line 104, a common line 112, at least a counter electrode 114, at least a pixel electrode 116, and a thin film transistor (TFT) 106. The IPS-LCD device 100 further comprises an insulating layer 103 electrically separating the common line 112 and the source line 102, an insulating layer 105 electrically separating the gate line 104 and the source line 102, and at least a via 113 electrically connecting the counter electrode 114 with the common line 112.
Referring to FIG. 4A and FIG. 4B, cross-sectional views taken along line II—II of FIG. 3 are illustrated. As shown in FIG. 4A and FIG. 4B, the IPS-LCD device 100 comprises a substrate 101, the source line 102, at least the counter electrode 114, at least the pixel electrode 116, a spacer 107, a color filter 109, and liquid crystal material 120. The source line 102, the counter electrode 114 and the pixel electrode 116 are disposed on the substrate 101. The presence of the spacer 107 provides room between the color filter 109 and the substrate 101 so as to fill in the liquid crystal material 120. The IPS-LCD device 100 shown in FIG. 4A does not supply an electric field to the liquid crystal material 120. Referring to FIG. 4B, an electric field is now supplied to the liquid crystal material 120. The liquid crystal material 120 is thus rotated and aligned in response to the electric field supplied. The curved lines each having an arrow at one end, as shown in FIG. 4B, represent the electric field lines.
It is clearly seen from FIG. 4B that the electric field supplied to the liquid crystal material 120 near the substrate 101 is stronger than that supplied to the liquid crystal material 120 near the color filter 109. Therefore, the rotation angle of the liquid crystal material 120 adjacent the color filter 109 is less than that of the liquid crystal material 120 adjacent the substrate 101. These inhomogeneous rotation angles of the liquid crystal material 120, resulting from the inhomogeneous electric field distribution, may reduce the light penetration rate, hence lowering the display quality.